How to connect strain gauge in the form of wheatstone bridge

[syedshaul]

HAI I am SYED , i am doing my project using strain gauges.

Problem description: I have 4 strain gauges bonded to an octagonal ring. The strain gauge i am using is METAL FOIL TYPE , GF(gauge factor) -2 and 320ohm resistance. The strain gauge has two terminals ,my question is
(1) Can anyone of the two terminals can be taken as positive and other as negative or is there any convention that the specified terminal should be taken as positive or negative...?

(2) I need help in connecting these 4 strain gauges in the form of Wheatstone bridge... ?

please help ... it would be very much helpful for my project i am very thankful for your help

 

[sophiecentaur]

HAI I am SYED , i am doing my project using strain gauges.

Problem description: I have 4 strain gauges bonded to an octagonal ring. The strain gauge i am using is METAL FOIL TYPE , GF(gauge factor) -2 and 320ohm resistance. The strain gauge has two terminals ,my question is
(1) Can anyone of the two terminals can be taken as positive and other as negative or is there any convention that the specified terminal should be taken as positive or negative...?

(2) I need help in connecting these 4 strain gauges in the form of Wheatstone bridge... ?

please help ... it would be very much helpful for my project i am very thankful for your help

What do you know about bridges in general? What produces 'balance' and 'imbalance?

 

[syedshaul]

What do you know about bridges in general? What produces 'balance' and

when all the 4 arms in a Wheatstone bridge has same voltage in my case Millivolt produced by strain gauge the output voltage is zero then it is called balanced bridge and when one arm has high voltage than other arms then there is a output voltage this is called unbalanced bridge.

 

[sophiecentaur]

OK, so maximum imbalance is when diagonally opposite pair of resistors increase and the other diagonal resistors decrease. Fit one pair to the front and one pair to the back of your flexing beam for maximum unbalanced volts.
Could you draw a diagram of that for me, to show you've got the idea?

 

[rezeew]

Hello Syed,

Connecting strain gauges in the form of a Wheatstone bridge is a common method used to measure small changes in resistance due to strain. In order to do this, you will need to follow a few steps:

1. First, you need to understand the principle of the Wheatstone bridge. It consists of a voltage source, four resistors (in this case, your strain gauges), and a voltmeter. The resistors are arranged in a diamond shape, with two opposite resistors connected in series, forming the top and bottom arms of the diamond, and the other two resistors connected in parallel, forming the side arms. The voltmeter is connected between the two parallel arms.

2. Next, you need to determine which terminals on your strain gauge are positive and negative. This can usually be found in the datasheet of your strain gauge, or by using a multimeter to measure the resistance between the two terminals. The terminal with a lower resistance is usually the positive terminal.

3. Once you have identified the positive and negative terminals, you can connect the strain gauges in the Wheatstone bridge configuration. The positive terminal of one strain gauge should be connected to the positive terminal of another strain gauge, and the negative terminal of the same strain gauge should be connected to the negative terminal of another strain gauge. This will form the top and bottom arms of the diamond. The remaining two strain gauges should be connected in parallel, with their positive terminals connected and their negative terminals connected. This will form the side arms of the diamond.

4. Finally, connect the voltage source to the two ends of the diamond, and connect the voltmeter between the two parallel arms. When a strain is applied to the strain gauges, the resistance of the strain gauges will change, causing a change in voltage across the voltmeter. This change in voltage can be used to calculate the strain.

I hope this helps you in connecting your strain gauges in a Wheatstone bridge configuration. If you have any further questions, please do not hesitate to ask. Good luck with your project!